1. Field of the Invention
The present invention generally relates to the field of networks. More particularly, the present invention relates to the field of network security.
2. Related Art
Computer systems and other electronic systems or devices (e.g., personal digital assistants, cellular phones, etc.) have become integral tools used in a wide variety of different applications, such as in finance and commercial transactions, computer-aided design and manufacturing, health care, telecommunication, education, etc. Computers along with other electronic devices are finding new applications as a result of advances in hardware technology and rapid development in software technology. Furthermore, the functionality of a computer system or other type of electronic system is dramatically enhanced by coupling these stand-alone electronic systems together to form a networking environment. Within a networking environment, users may readily exchange files, share information stored on a common database, pool resources, and communicate via electronic mail (e-mail) and via video teleconferencing.
In a network environment, there are three basic techniques used to achieve mutual authentication between two parties, whereas each party is an electronic system within the networked environment such as a wireless client electronic system or a network access point electronic system. In the first basic technique, public key cryptography is used. According to public key cryptography, the two parties sign (i.e., provide a digital signature for) a message using their respective private keys, while they authenticate (i.e., verify the origin of) the message using the other party's public key. In the second basic technique, the two parties hold a shared secret. Each party signs a message using the shared secret, while the other authenticates the message using the shared secret. In the third basic technique, the two parties hold a shared secret with a third-party such as an authentication authority. Each party signs the message using the third-party shared secret. The message is forwarded to the third party by the receiving party for verification or transformation. When the third-party verifies, it simply tells the receiving party whether the message is authentic. When the third-party transforms, it re-signs the message with the receiving party's shared secret, returning it to the receiving party for verification.
Each of the three basic techniques has its strengths and weaknesses. From a purely security perspective, implementing public key cryptography is preferred over the other basic techniques. However, public key cryptography requires a significant public key infrastructure. For particular applications that do not need this public key infrastructure for other purposes (e.g., IPSec), deployment of the public key infrastructure can create a significant market barrier to prospective customers of network environment equipment.
The next preferred basic technique from a security perspective implements a secret shared between two parties. This basic technique is inferior to public key cryptography because signing a message with such a shared secret does not actually authenticate the sender of the message. This basic technique just raises the receiving party's confidence that the sender of the message knows the shared secret. This may seem like an insignificant distinction, but there are certain types of attacks against authentication protocols by using shared secrets (e.g., reflection attacks) that complicate those authentication protocols.
The third basic technique, i.e., implementing secrets shared with a third-party, is the least attractive from a security perspective. However, the third basic technique is, in many cases, the most attractive approach from a management and deployment point of view. The use of public key cryptography and shared secrets imposes non-trivial administration burdens on the deploying organization. As previously indicated, public key cryptography normally requires the deployment of a Public Key Infrastructure, which is costly from an initial investment as well as an operational perspective. Pair wise shared secrets require extensive management of those secret keys, since each sending party must obtain, store, and manage (e.g., revoke) the secret keys shared with all other parties in the network environment. When implementing secrets shared with a third party, each party need only obtain and store one secret key. Many secret key management functions can be centralized in the third-party itself.
In a wireless network that requires a client electronic system (which is mobile and is capable of roaming) to authenticate itself to the wireless network before the client electronic system is allowed to use the resources of the wireless network, the repeated use of strong, computationally complex authentication methods can be a significant burden to both the client electronic system and the wireless network. In particular, a client electronic system that is roaming may be unable to authenticate itself to a network access point electronic system of the wireless network because the strong, computationally complex authentication method may require a longer period of time to complete than the period of time available before the client electronic system switches to another network access point electronic system of the wireless network. Typically, the strong, computationally complex authentication method may take a few seconds to complete.
Therefore, what is needed is a method and system for using a key lease in a secondary authentication protocol after a primary authentication protocol has been performed.